The present invention relates generally to systems for discriminating between different types of engine operating condition sensors, and more specifically to such systems operable to automatically select an appropriate sensor processing algorithm based on the detected sensor type.
Oil pressure sensors for internal combustion engines have heretofore been implemented with a number of different types of pressure sensing devices. For example, one type of oil pressure sensing device that is commonly implemented is an analog pressure sensor producing an analog voltage that is proportional to the engine oil pressure. Another type of commonly implemented oil pressure sensing device is an oil pressure switch having a pressure switch point set at a specified pressure level. At engine oil pressures below the pressure switch point the oil pressure switch produces one voltage level, and at oil pressures above the pressure switch point the oil pressure switch produces a different voltage level. While both of the foregoing types of oil pressure sensing devices are widely used, each require different oil pressure signal processing algorithms for producing oil pressure values to be monitored by the vehicle operator and/or to be used by one or more engine control algorithms.
In many engine applications, the oil pressure sensing device may be implemented with either of the foregoing oil pressure sensing device types, and the type of oil pressure sensing device used with any one engine may not be known until after the engine is completed and accessorized. This then requires a subsequent determination of oil pressure sensing device type and attendant implementation of an appropriate oil pressure signal processing algorithm. What is therefore needed is a system for automatically determining the type of oil pressure sensing device implemented in an engine, and then automatically selecting and implementing an appropriate oil pressure signal processing algorithm based on the detected oil pressure sensing device type.
The present invention may comprise one or more of the following features and combinations thereof. A system for automatically selecting an oil pressure sensor processing algorithm based on oil pressure sensor type may comprise an oil pressure sensing device producing an oil pressure signal indicative of oil pressure in an internal combustion engine, wherein the oil pressure sensing device may be one of an analog oil pressure sensor and an oil pressure switch, and a control computer having an analog input and a switch input with the oil pressure sensing device electrically connected to one of the analog and switch inputs. The control computer may be configured to identify the oil pressure sensing device as the analog oil pressure sensor and process the oil pressure signal according to a corresponding analog oil pressure sensor processing algorithm if a voltage level at the analog input is within a predefined voltage range while a voltage level at the switch input is at or near a first voltage level, and to identify the oil pressure sensing device as the oil pressure switch and process the oil pressure signal according a corresponding oil pressure switch processing algorithm if the voltage level at the switch input is at or near a second voltage level different from the first voltage level.
The system may further include an ignition switch having at least an off position and an on position, and the control computer may be responsive to the ignition switch switching from the off position to the on position to monitor the voltage level at the analog input and the voltage level at the switch input.
The predefined voltage range may be defined between a third voltage level greater than ground potential and a supply voltage, and the first voltage level may be the supply voltage. The second voltage level may be ground potential.
Alternatively, the control computer may be configured to identify the oil pressure sensing device as the analog oil pressure sensor and process the oil pressure signal according to a corresponding analog oil pressure sensor processing algorithm if a voltage level at the analog input is at or near a first voltage level and a voltage level at the switch input is at or near a second voltage level different than the first voltage level and if the oil pressure sensing device was identified in a preceding engine operating cycle as the analog oil pressure sensor. In this case, the first voltage level may be ground potential, and the second voltage level may be a supply voltage.
Alternatively still, the control computer may be configured to identify the oil pressure sensing device as the oil pressure switch and process the oil pressure signal according to a corresponding oil pressure switch processing algorithm if a voltage level at the analog input is at or near a first voltage level and a voltage level at the switch input is at or near a second voltage level different than the first voltage level and if the oil pressure sensing device was identified in a preceding engine operating cycle as the oil pressure switch. In this case, the first voltage level may be ground potential, and the second voltage level may be a supply voltage.
In any case, the control computer may be configured to conduct an initial identification of the oil pressure sensing device if the oil pressure sensing device was not identified in a preceding engine operating cycle. In this case, the system may further include an engine speed sensor producing an engine speed signal indicative of engine rotational speed, and the control computer may be responsive to the ignition switch switching from the off position to the on position to conduct the initial identification of the oil pressure sensing device by monitoring the voltage level at the analog input and the voltage level at the switch input and determining a first oil pressure sensing device type based on the voltage levels at the analog and switch inputs. The control computer may identify the oil pressure sensing device as the first oil pressure sensing device type if the engine speed signal remains below an engine speed threshold for a predefined time period.
The control computer may further be configured to determine a second oil pressure sensor device type based on the voltage levels at the analog and switch inputs if the engine speed signal does not remain below the engine speed threshold for the predefined time period, and the control computer may identify the oil pressure sensor device as the first oil pressure sensing device type if the first and second oil pressure sensor device types are identical and otherwise identify the oil pressure sensor device as a preselected one of the analog oil pressure sensor and the oil pressure switch. The preselected one of the analog oil pressure sensor and the oil pressure switch may be the oil pressure switch, or may alternatively be the analog oil pressure sensor.
These and other objects of the present invention will become more apparent from the following description of the illustrative embodiments.